Field of the Invention
The present invention relates to a hydrodynamic converter having the features of the preamble of claim 1 and to an adjustment device for a converter of this type. A converter of the type in question is known from U.S. Pat. No. 3,151,457, for example.
Hydrodynamic converters or torque converters have at least three blade wheels, i.e. a pump wheel, a turbine wheel and a stator, which deflect a flow circulating in a working space. This basic construction is referred to as single-stage. If the converter has a device which enables the circulatory flow to be changed during operation, this is a variable converter. One example of a converter of this type is the adjustable converter, the blades of which can be adjusted from outside during operation.
The pump wheel, which is coupled to the drive, transmits the pump wheel torque produced by the drive to the operating medium flowing in the working space. The operating medium transmits the torque to the turbine wheel, which is coupled to the output. In addition, a deflection of the operating medium is produced by the stator, which is in the working space and is firmly connected to the housing, and by the guide blades thereof. Through the deflection of the operating medium at the guide blades, the torque output to the turbine wheel by the operating medium is intensified. Thus, the output torque can be up to 2.5 to 12 times the input torque, for example.
Converters with rigid blades have a single operating state, in which an optimum incident flow direction for the blades of all the wheels is specified. If there are deviations from this operating state, there are not only frictional losses but additional flow losses, which are all the greater, the greater the deviations from the optimum operating state. For this reason, adjustable stator and/or pump-wheel blades are installed.
The prior art includes hydrodynamic converters which allow adjustment of the pump wheel blades.
U.S. Pat. No. 3,330,112 shows a torque converter, the pump blades of which are pivotably mounted. The angle of attack of the blades can be changed by means of a deflection device. For this purpose, the pump blades are each connected to a common adjusting ring by a joint, thus allowing the angle of attack of the pump blades to be set by means of a rotary motion of the adjusting ring relative to the pump wheel. The adjusting ring is coupled mechanically, by means of toothing, to a subsection that can be moved in the axial direction of the drive shaft, thereby making it possible to produce the desired relative rotary motion of the adjusting ring. The translational movement of the subsection is controlled by two mutually separate pressure chambers.
U.S. Pat. No. 3,151,457 discloses a converter, wherein a subregion of the blade of the pump wheel can be set by means of a deflection device. For this purpose, a cylinder is supplied with hydraulic fluid via a pressure channel, which is passed into the interior of the pump wheel. By means of a stroke motion of the cylinder piston, the cylinder turns an adjusting ring. By means of the turning of the adjusting ring, the desired change in the angle of the pump wheel blades is produced.
The required pressure must be built up over a relatively long distance via the pressure channel. Moreover, appropriate sealing of the pressure channel must be ensured in the rotating components of the converter in order to sustain a change in the angle of the subregion of the pump wheel blades over a prolonged period in the operating state of the converter.